HIAbout two weeks ago the city sewer line clogged and my finished basement got the worst of the back-up (2-3 inches). Some of the neighbors mentioned that this happened about 20-23 years ago to my house and again the city was responsible for their line. Now I'm wondering if I should have a valve installed either inside my basement bathroos or outside in the yard? I've heard pros and cons to both methods and am thoroughly confused now. Do you think I should even bother having one put in since there was such a time gap between back-ups and just have the city clean out and inspect the holes and line more frequently?Any help would be appreciated....